The force admitted there were zero fines issued from July 24, when face coverings were made mandatory in shops, until August 14.
But it has handed out two either before or after then, a spokesman said, with coverings required on public transport since June 15.
"We will continue to engage with people and explain the rules, but we will enforce with people who deliberately flout or ignore them," he said.
When the requirement to wear a face covering was extended to other indoor settings where people are likely to come into contact with others they don't normally meet, including museums, galleries, cinemas, and places of worship, Rachel Hanley, chairwoman of the Lancashire Police Federation, said officers would need the public's help.
She said: "The practicalities of policing this latest change in regulation will be challenging, but policing will do all it can to keep the public safe.
"We do, though, need the public to support us.
"As per the current guidance, officers will be doing all they can to encourage people to do the right thing, without resorting to enforcement.
"Parts of the new regulation will be difficult, if not impossible, to enforce and sadly I fear it will once again be the already stretched police service taking the brunt of people's frustrations."
In England, face coverings must be worn in shops and many other indoor places, including post offices, banks, salons, visitor attractions and entertainment venues, libraries, public areas of hotels, community centres, and funeral homes.
Some people are exempt, including children under 11 and those unable to wear masks because of mental or physical impairment, but those who aren't face - if they are caught by police - maximum fines of £3,200.
"The best available scientific evidence is that, when used correctly, wearing a face covering may reduce the spread of coronavirus droplets in certain circumstances, helping to protect others," the Government said.
Lancashire Police said: "Lancashire remains in the midst of a pandemic. The regulations are there to prevent the virus spreading, protect people's health, and keep everyone safe, and we won't hesitate to enforce where we need to.
"Larger numbers of young people are contracting the virus - they may not get really ill but they may infect friends and family who are much more vulnerable.
"We know the vast majority of people in Lancashire will do the right thing and will support our officers in enforcing the law when the minority choose to deliberately ignore it and put their communities at risk."